Coating machines for pharmaceutical, confectionary and the like, are usually equipped with a rotary hollow drum, in which the products to be coated are introduced and sprayed with a liquid mixture aimed at forming the coating.
Inside the rotary drum, also called coating pan, the products are subsequently exposed to a stream of hot air, so as to cause drying of the coating layer.
In several drying devices used to perform this operation, the air is supplied in the pan and exhausted therefrom at a distance above the tumbling products.
Alternatively, the air is supplied and exhausted via suitably shaped bodies which are immersed in the heap of products.
In the European Patent N. 0.131.152, granted to the Applicant, there is disclosed a drying device in which the air is freely injected into the rotary pan, while it is exhausted by suitable perforated hollow bodies immersed in the heap of products.
Good results have been obtained by means of this device, in particular the coating speed has been increased and granular remains, usually left after the coating operation, have been avoided.
The hollow bodies are fastened (see e.g. the Application No. 21924A/89 of the Applicant) to respective tubular members, which are removably fixed to each other so as to define a pipe arranged in coaxial relation to the pan.
The air to be exhausted from the rotary pan and that is drawn off via the hollow bodies passes through the pipe.
The tubular members can be disassembled and the hollow bodies can be detached therefrom thus allowing to easily carry out cleaning and/or maintenance operations of the same hollow bodies and pipe.
When the rotary pan is small and/or medium in size, the operator can carry out the above mentioned disassembling operation directly through the front opening of the pan.
When the rotary pan is rather big in size, the above mentioned operations cannot be performed from outside, therefore it is necessary for the operator to enter the pan, with all the inconveniences resulting therefrom.
Consequently, performing inside cleaning operations, in particular of the air exhaust pipe, is very uncomfortable and difficult, specially with big rotary pans.